Carbon nanotubes (CNTs) are unique molecular structures that exhibit interesting and useful properties and may be utilized for a variety of devices. Example CNTs include single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). SWNTs have a cylindrical sheet-like, one-atom-thick shell of hexagonally-arranged atoms.
CNTs have been used in a variety of applications that are increasing in number and diversity as their manufacture and implementation becomes more widespread. For instance, SWNTs have been increasingly considered for and/or used with advanced electronics applications. Carbon-based SWNTs are hollow structures composed, at least partially, of carbon atoms. SWNTS can be doped with other elements such as metals, boron and nitrogen. SWNTs are increasingly being used as conductors (e.g., nanowires) and to form electronic components such as field effect transistors (FETs), switches and others.
SWNTs have a tendency to grow in a manner that exhibits metallic and semiconducting mixtures due to various chiralities (e.g., geometric characteristics). For example, SWNTs grow as a mixture of bundled semiconducting SWNTs (S-SWNTs) with metallic SWNTs (M-SWNT). The M-SWNTs show ballistic behaviors and can be ideal for conducting connectors and electrodes for electronic devices. The S-SWNTs show high mobility and can be useful for high-current and high-speed nanotube FETs. By contrast, MWNTs tend to grow as metallic MWNTs.
The above issues as well as others have presented challenges to the isolation of semiconducting and/or metallic nanotubes for a variety of applications.